Screw jack



Feb. 16 1926. 1,573,611

A. JOHNSON SCREW JACK Filed April 1'7, 1924 5 7 -Ls'- l 1 1 w 15 I 14 v 5 /2 I 5 gnwnloz l) 7 1 I 1072116011,

combination and arrangement of parts here-- Patented Feb. 16, 1926.

. A UGUsT Jonnson-os'rorvomr, MIN-NEsOTAQ v SCREW a plication fiied a ri 17,

T0 (ZZZ whom it mag concern: v

Be it known that ;[,-Aricrisr JoHNsoN, a

citizen of the United States, residing at-T0i vola, in the county of St. Louisand State of Minnesota, have invented certain new and useful Improvements in Screw Jacks;*and Ido hereby declare the tollowingjto be a full, clear, and exact description of the in-f vention, such as will enable others skilled in theart to which it appcrtainsto make and use the same; a This invention relates to lifting jacks, and more particularly toilitting jacks of that type embodying a support, af lower screw having threaded engagement with-the support, and an upper screw having threaded engagement with the lower screw.

The invention has for its primary oloject the provision of a lifting jack of the character stated with means through the medium of which the lower screw maybe turned up or locked against downward rotative movement with'respect to the support and. with means through the' medium of'which the upper screw may be turned up 'or locked against downward rotative movement with respect to the lower screw. I r v A further object of the invention is the provision of a simple,durable and light lift ing jack of the character set forth.

With the above and other objects in view, the invention consists in the "construction,

iiiatter fully described and claimed, and illust 'ated in the accompanying ClIQWIII wherein Figureil is a View in side elevation of a lifting jack constructed in accordance with my invention, 7

Figure 2 is a sectional view taken on a plane extending vertically and centrally through the lifting-jack,

Figure 3 is a detail horizontal sectional view taken on the plane indicated by the line 33 0f-Figure 1, and g I Figure 4 is a similar view taken on the plane indicated by the line 44 of Figure 1.

The lifting jack comprises a support which consists of a base 1 and a pedestal 2. The support is hollow and angular in cross section. The sides of thepedestal 2 curve. inwardly and upwardly and are ofincreased thickness at their upper ends, as shown at 3, which ends are formed to provide a vertically arranged screw threaded opening 4:.

JACK.

1924. Serial mlj' zomozp At oppositesides, with handles 5-. v The opening the pedestal 2isprovid'ed receives the lower ,hollow screw'6' which is internally screw threaded ad acent t's upper end to per-hollow screwi', H

A screwturning and screw her or nut S isniount'ed upon the lower 6 for a'dJustinent into contact with screw at the upper endoi tliisscrew orfor adjustment into contact with the upper end or the pedestal 2. When the member or nut 8 is in contact with the flange 9, the lower screw 6 may be turned up with respect to the support through the medium of a lcvcr,not

shown, engaged in one of. a plurality ot'opeuings 10in the member or nut 8. V'Vhen this member or nut 8 is in contact with the upper end of the pedestal 2, the lower screw,

6 is locked to the support againstany downward rotative movement with respect there'- The upper screw 7 is PTOVZClGd WIth a similar member ornut 11.. This member or nut 11 is adapted to be adjustedupo'n the V upper. screw 7-1nto contact with a shoulder turned up with respect to the lower screw 6 through themedium oifa lever, inserted in one of a plurality of openings 13 in the nut.

lVhen the nut 11 is in contact with the upper i end of the lower screw 6,'the upper screw 7 is locked against any downward rotative no movement with respectto the lowerscrew The upper end of the upper screw 7 is reduced to provide a journalld upon which is rotatably mounted a cap or rest 15. The

upper end of the journal la is flanged over asshown at 16 to prevent the displacement of the cap or rest 15 which is provided with a load receiving groove 17.

-As the support,which comprises the base 1 andpedestal :2, together-with the screws 6 and 7,;are of hollow formation, it should be apparent that the jack is of compara-,

tively light weight. It should be apparent that thescrews 6 and 7 may be readily adjusted up or down withrespect to the sup- 1 port and with respect to each other, and that they may be readily locked against downward rotative movement with respect to thesupport and with respect to each other. The openings 10 in the member or 20 receive the up j [66 locking inemnut 8 are arranged tangentially with respect to the lower screw 6 and the openings 13 in the member or nut 11 have a diametrical arrangement with respect to the upper screw 7. To permit the lower screw to be held against rotation while adjusting the member or nut S thereon, the flange 9 thereof is of polygonal outline to permit it to be engaged by a wrench.

What is claimed is A screw jack comprising a support, a lower screw having threaded engagement with the support and provided at its upper end with a polygonal shoulder, a member provided with a plurality of openings and threadedly mounted upon said screw for adjustment into contact with said support to lock the screw against downward rotative movement with respect to the support and for adjustment into contact with said shoulder to permit the screw to be turned outwardly with respect to the support an upper screw having threaded engagement with the lower screw'and provided at its upper end with a shoulder, a member provided with a plurality of openings and threadedly mounted upon the upper screw for adjustment into contact with the upper end of the lower screw to lock the upper screw against downward rotative movement with respect to the lower screw and for adjustment into contact with the shoulder at the upper end of the upper screw to permit said upper screw to be adjusted up ardly with respect to the lower screw, and a cap or rest carried by the upper screw.

In testimony whereof I afiix my signature.

AUGUST JOHNSON. 

